Method for producing film
The separator production method in accordance with an embodiment of the present invention includes a coated article taking up step of taking up a separator original sheet by winding the separator original sheet on an outer peripheral surface of a core while oscillating the core in the rotation axis direction; a coated article winding off step of winding off the separator original sheet, which has been taken up in the coated article taking up step, from the core; and a transferring step of transferring the separator original sheet, which has been wound off in the coated article winding off step, such that a state of being distorted in a wavelike manner in the transverse direction is maintained.
1. A method for producing a film, said method comprising the steps of:
taking up a film by a first step of winding the film on an outer peripheral surface of a core while oscillating the core in a rotation axis direction, such that the film is in a state of being distorted in a wavelike manner in the rotation axis direction;
a second step of winding off the film, which has been taken up in the taking up step and is in the state of being distorted in the wavelike manner in the rotation axis direction, from the core; and transferring the film, which has been wound off in the second winding off step, such that the state of being distorted in the wavelike manner in the rotation axis direction is maintained.
2. The method as set forth in claim 1 , wherein:
in the transferring step, the film is transferred by a plurality of transferring rollers which are provided so that rotation axes of the respective plurality of transferring rollers extend in a direction perpendicular to a machine direction of the film and a thickness direction of the film and are aligned in the machine direction.
3. The method as set forth in claim 2 , wherein:
a distance between rotation axes of adjacent two of the plurality of transferring rollers is equal to or less than a value obtained by the following formula:
Oscillation cycle T×taking-up speed V÷4
where an oscillation cycle of the core in the taking up step is defined by T [s], and a taking-up speed of the film in the taking up step is defined by V [m/s].
4. The method as set forth in claim 1 , further comprising the step of:
slitting the film, which has been transferred in the transferring step, into parts each of which has a predetermined product width.
5. The method as set forth in claim 1 , wherein:
a functional layer is provided on at least one of a front surface and a back surface of the film.